1. Field of the Invention
The present invention relates to an excessive flow detection circuit, a terminal apparatus and a network node. More particularly, it relates to an excessive flow detection circuit in the transmission terminal of fixed-length or variable-length packets or a network node (a router or the like), and such a terminal apparatus and network node.
2. Description of the Related Art
In the “Triple Play” being a Next Generation Network (NGN), a plurality of services are integrated on an identical network (IP network), and also a service which transfers the stream type traffic of telephonic voices, broadcasting videos etc. is rendered through the Internet Protocol (IP) network. In such a service which transfers the stream type traffic of voices, videos etc., it is required to transfer the traffic with high communication qualities (low delay, low fluctuation and low loss). Therefore, needs for techniques which guarantee the communication qualities have risen for the IP network. The development and installation of Quality of Service (QoS) control technology which can control the transfer with the qualities guaranteed have been required also of individual nodes (routers or the likes) constituting the IP network.
Basically, it is general in the node (router or the like) to transfer the traffic of voices, videos etc. by a PRIORITY CONTROL relative to a data type traffic. In, for example, an ATM network being a related-art technique, a traffic class called “CBR (Constant Bit Rate)” has been applied. With the mere application of the PRIORITY CONTROL, however, there is the risk that an excessive traffic wider than the maximum band supposed and set as the stream type traffic beforehand might flow in by a cause such as the setting error of a network manager or a malicious attack from a user, and it is sometimes impossible to prevent the excessive traffic. The occurrence of the inflow is influential on the communication qualities of the majority general users who are communicating while observing normal traffic standards. The installation of band monitoring and controlling functions has been simultaneously required in order to prevent the influences.
A UPC function (policer function) has been generally known as the band monitoring function in the node (router or the like). The UPC function is a general-purpose function for monitoring a band in the node (router or the like), and it decides whether or not a flow rate exceeds the band which an operation manager has set every flow, every flow (for example, every session of a telephonic conversation) to-be-handled (refer to, for example, Patent Document 1 being JP-A-2000-349812, which shall be termed “related-art technique 1” below).
Meanwhile, data analysis means includes a fast extraction technique wherein frequent item sets are extracted from data in a plurality of combinations which are utilized for a basket analysis etc. The fast extraction technique is a method wherein the data in the plurality of combinations are applied to the combinations (frequent item sets) of a sender address, a receiver address, a port No., etc. The data analysis method is a general-purpose function, and it extracts the (plurality of) major frequent item sets fast from among the data in the plurality of combinations. The algorithm has the merit that the installable amount of resources is a fixed scale which is not proportional to the number of flows (refer to, for example, Patent Document 2 being JP-A-2005-285048 and Non-patent Document 1 being “Stream Mining for Network Management” by Kenichi YOSHIDA et al., IEICE TRANS, COMMUN., VOL. E89-B, NO. 6, JUNE 2006, which shall be termed “related-art technique 2” below).